ارزیابی تحمل گرمای پایان فصل ژنوتیپ‌های جو با شاخص‌های تحمل و حساسیت به تنش

با توجه به اینکه تنش گرما به‌ویژه گرمای پایان فصل گسترده‌ترین نوع تنش گرمایی در جهان، مخصوصا در مناطق نیمه‌گرمسیری به‌شمار می‌رود و به‌عنوان یک محدودیت بزرگ در تولید عملکرد پایدار محصولات زراعی از جمله جو است، از این‌رو شناسایی ژنوتیپ‌های متحمل به گرما، راهکار ارزشمندی در مقابله با این تنش است. این تحقیق به‌منظور ارزیابی تحمل به گرمای پایان فصل و شناسایی ژنوتیپ‌های متحمل جو با استفاده از شاخص‌های تحمل به تنش در سال زراعی 95 - 1394 در مزرعه پژوهشی دانشگاه گنبد کاووس انجام شد. مواد گیاهی آزمایش، 120 ژنوتیپ جو بودند که در قالب طرح بلوک‌های کامل تصادفی با دو تکرار در دو شرایط بدون تنش و تنش گرما ارزیابی شدند. نتایج حاصل از این آزمایش نشان داد که بیشترین میانگین عملکرد در شرایط بدون تنش مربوط به ژنوتیپ torsh و در شرایط تنش مربوط به ژنوتیپ line143 - 2 بود. مقایسه شاخص‌ها نیز نشان داد که شاخص‌های yi، sti، gmp و mp بیشترین همبستگی معنی‌دار با عملکرد در شرایط بدون تنش و تنش را داشتند و شاخص‌های برتر این آزمایش برای غربال ژنوتیپ‌های متحمل به گرما بودند. تجزیه خوشه‌ای بر اساس شاخص‌ها و عملکرد در شرایط تنش و بدون تنش، ژنوتیپ‌های مورد بررسی را به سه گروه تقسیم کرد. در مجموع، نتایج حاصل از تجزیه خوشه‌ای و تجزیه به مولفه‌های اصلی نشان داد که ژنوتیپ‌های torsh، zarjo و shori4 بیشترین تحمل و ژنوتیپ‌های line105 - 2، nosrat، line98 - 2 و fajr30 کمترین تحمل به تنش گرما را داشتند.

evaluation of late season heat in barley genotypes using some susceptibility and tolerance indices

introductionbarley is one of the most important crops in the world and ranks fourth in terms of nutritional importance and area under cultivation among cereals after wheat, corn and rice, but it has ranks first in terms of the extent of cultivation in a variety of climates. the world’s food production is severely limited by environmental stresses. one way to sustain production for the world’s growing population is to minimize the reduction in production caused by these tensions. given that heat stress, in particular late season heat is the most widespread type of heat stress in the world, especially in the subtropical regions, and as a major constraint in the production of sustainable crop yields, including barley. therefore, identifying heattolerant genotypes can be a valuable solution to this problem. the present experiment was undertaken to understand the impact of high temperature on yield and its attributing traits and to select heat stress tolerant parents and cross combinations for future breeding program.materials and methodsto fulfill the requirement of this objective, the experiment was conducted in two environments i.e. normal and heat stress. infact this study was performed to evaluate the heat tolerance at the end of the season and to identify barley tolerant genotypes using stress tolerance indices on experimental farm of the gonbad kavous university during the growing season of 20152016. the experimental plant materials were 120 barley genotypes which were evaluated in a randomized complete block design with two replications under two conditions without stress and heat stress. in addition, seeds of each genotype were grown in two meter rows with 20cm distance between the rows and the plant density was 270 plants per m2.results and discussionthe results of this experiment showed that the highest yield mean in nonstress conditions was related to genotype torsh and in stress conditions was related to genotype line1432. the results of analysis of variance for yield trait showed that the differences between genotypes and the interactions of genotype and environment were significant at the level of one percent for the trait, which indicates high diversity and different reactions of cultivars and lines in different environments. comparison of indices also showed that yi, sti, gmp and mp indices had the highest significant correlation with yield under nonstress and stress conditions and the superior indices of this experiment were for screening heat tolerant genotypes. cluster analysis based on indices and yield under stress and nonstress conditions divided the studied genotypes into three groups.conclusionoverall, the results of cluster analysis and principal component analysis showed that genotypes torsh, zarjo and 4shori had the highest tolerance and genotypes line105, nosrat, line982 and fajr30 had the lowest tolerance to heat stress. obviously, it is necessary to repeat the experiment in other places to be surer of these results and to obtain definitive results. on the other hand, to obtain heattolerant cultivars, it is recommended to cross the torsh, zarjo and 4shori genotypes, and to locate heattolerant control genes, tolerant genotypes (torsh and zarjo) cross with sensitive genotypes (line105 and nosrat) can be used as two parents.